Crushing apparatus



Feb. 20, 1934. N. D. LEVIN CRUSHING APPARATUS Original Filed May 14,1929 Patented Feb. 20, 1934 CRUSHIN G APPARATUS Nils D. Levin, Columbus,Ohio, assignor to The 1 Jeffrey Manufacturing Company, Columbus,

Ohio, a corporation of Ohio Application May 14, 1929, Serial No. 362,951

r Renewed July 30, 1932 35 Claims.

The present invention relates to certain new and useful improvements incrushing apparatus, and particularly to apparatus of the class whereinmaterial may be reduced by contact with radia: ally extending portionsof a plurality of beaters attached to a rotor adapted to revolve withina crushing chamber.

Machines having chambers within which are mounted rotors providedv withpivotally attached 19 boaters adapted to engage'material within thechamber are well known in the art, having been commonly used for manyyears. In order that the heaters of such machines may be effectivelyheld in radial projection, the rotors must revolve at relatively highspeed, commonly about 1000 revolutions per minute. Owing to the velocityof the boaters, coal, limestone and similar friable material, whentreated in such a machine, are reduced to a powder entirely too fine formany purposes of use. Attempts have been made to overcome thisdifiiculty by rigidly securing the heaters in radial extension upon therotors. When the heaters are so rigidlysecured, the rotors may berevolved at any desired speed lower 95 than is possible with machines ofthe common pivoted beater class. In practice, such rotors usuallyrevolve at about 250 to 300 revolutions per minute. While the productproduced by rigid hammer machines of the class described, is extremelysatisfactory, such machines possess certain inherent defects whichrender'them generally undesirable.

In the mining and quarrying operations whereby coal, limestone and thelike, are obtained from their native beds, tools, broken parts ofmachinery used in the mining and quarrying operations, and bolts, nuts,or other relatively small parts accidentally detached from the cars orother equipment by which said material is handled, occasionally becomemixed with the material which is to be crushed. When such uncrushableobjects are engaged by rigid heaters such as above described, themachine is subjected to severe strains and shocks which sometimes break.or otherwise seriously injure the machine.

It is the especial object of this invention to provide in a machine ofthe class described, improved beaters adapted to be moved to and held bycentrifugal force generated by the rotation of the rotor, in operativeposition analogous to that of the rigid heaters above referred to butwhich, upon contacting with unpulverable objects, are adapted to bemoved inwardly of the rotor along lines substantially radial thereofthereby avoiding the injurious shocks and strains and protecting themachine against such injury.

The means whereby I attain this, and other objects are fully set forthin the followingspecification and illustrated in the accompanyingdrawing of which:

Fig. 1 is a transverse sectional View of a crushing machine equippedwith the devices of my invention.

. Fig. 2 is a plan view of the rotor of the machine shown in Fig. 1. 3

Fig. 3 is a perspective view of one of the heaters used in the machineshown in Fig. 1.

Like numerals refer to similar parts in the several figures.

Referring to the drawing, it will be seen that as here shown, myimproved apparatus consists of a reducing element which maytake variousforms, but in this illustration of the invention is in the form of askeleton rotor adapted to revolve within a casing arranged to confinethe material, the rotor being shown in the present instance as revolvingabout a horizontal axis. The casing comprises. a main supporting frame 1and a housing 2 which are joined together, as here shown, along thehorizontal central plane of the rotor, although variations in thisarrangement may be made. The main frame 1 has end walls and side Walls,though not necessarily formed of a single casting. At the end of themain frame l are journal bearings, not shown in the drawing,

'which may he of any suitable type and are designed to support the rotorelement 3 of the machine. J ournaled in these hearings is a shaft 4 toone end of which is attached a suitable pulley or other device, by whichthe rotor may be connected in any suitable manner with any convenientsource of rotative power, but as such devices are well understood in theart, and as they form no part in the present invention, theirillustration and descriptionis not thought to be required at this time.Attached to the main frame 1 in any suitable manner and extendinglongitudinally thereof are the grate bars 5 which form asemi-cylindrical floor for the pulverizing chamber arrangedconcentrically with the shaft 4 and the spacing of these grate bars 5controls the size of the maximum fragments of the product of themachine.

Mounted upon the shaft 4 in spaced relation longitudinally thereof, area plurality of discs 6 which are secured to the shaft in any preferredmanner, as by the key 7 to revolve therewith.

Disposed concentrically with the shaft 4 and supported in apertures ofthe discs 6 are a plurality 11o of rods 8, upon which are pivotallysupported the beaters 9, designed to engage and reduce the materialwhich is to be crushed. The beaters 9 are preferably formed of castingsof a refractory alloy of iron and comprise an elongated body portion 10having an aperture 10' at one end through which extends a pivot rod 8.Formed at the distal end of body portion or arm 10 is a bi-lateralmaterial engaging head comprising two oppositely disposed extensions 11and 12. The head end of the heater is provided with a re entrant recessor depression 13 having bounding walls 14 and 15 equally spaced atopposite sides of the longitudinal axis of the beater.

The proportions of the parts are such that a beater 9, mounted intrailing relation on one rod 8, extends in such proximity to itssucceeding rod 8, that movement of the beater about its pivotal supportwill cause eventual abutment of walls 14 or '15 with the succeeding rod.As is clearly evident from Fig. 3, in'the embodiment shown, two beatersare mounted between each pair of plates so that the pivot rods of oneset of beaters serve as the abutment rods of the adjacent set or sets ofbeaters. For example, referring to Fig. 1, it will be seen that rod 8,at the top of the rotor, serves as an abutment member for the beatershown in full lines at the upper left of the figure, and the same rodserves as the pivotal support for the beater at the other side of theplate which is shown in dotted lines.

When the rotor 3 is set in motion, the beaters tend to move outwardly,this outward movement being arrested through abutment of walls or lugs15 with rods 8. The heater arms are of such length relative to thediameter of the rotor that when the heaters are in this fully projectedposition, their arms lie tangent to an imaginary circle indicated at 16,Fig. 1, the length of the arms being greater than the radius of thecircle and the length of the beaters as a whole being greater than thediameter of this circle. This i relation of parts, which calls for abeater of considerable length, enables the beater heads to be heldoutwardly under relatively small centrifugal force, their resistance toinward movement being proportionatey great as compared to the pivotedbeaters heretofore used.

When an unpulverable object such as shown at 17 is encountered, thebeater in question is caused to move temporarily inwardly of the rotorwithout damage to the machine and even without substantial shock. Thisis largely due to the fact that faces 11' and 12' of the beaters formobtuse angles with the arms and thus project from the rotor periphery ata rearward angle to radial lines intersecting the points of junction ofthe arms and the angular faces. The beater at the upper left of Fig. 1is assumed to have struck object 17 and thus moved temporarily from theindicated dotted line position to the full line position.

The lateral faces of projections 11 and 12 are rearwardly convergent onsimilar arcs these projections being of similar size and shape to form areversible beater. In one position of the beater, wall 14 of recess 13serves to limit the inward movement of the beater and wall 15 itsoutward movement, while upon reversal of the beater the functions ofthese walls are reversed. In the preferred construction, the size ofprojections 11 and 12 of the beaters is such, in relation to theabutment lugs defined by walls 14 and 15, that inward movement of thebeater head is not positively arrested until its working portion isentirely within the peripheral outlines of the rotor. Such being thecase and in view of the fact that the pivot rods 8 are likewise withinthe peripheral outlines of the rotor, each beater under certainconditions may lie completely within the rotor body 3.

Occasionally, through the breaking of a belt, the blowing of a fuse, orother cause, revolution of the rotor is suddenly interrupted allowinguncrushed material within the hopper to fall into the spaces between therotor and the grate bars 5. Under such circumstances, the machinesheretofore constructed have become completely choked rendering necessarythe opening of the casing and the digging out of this congested materialbefore revolution of the rotor could be restored. By the peculiarconstruction and mounting of the beaters herein described, such chokingis avoided since the beaters, being crowded within the peripheraloutlines of the rotor, offer little or no resistance to revolution ofthe rotor. When the power connection has been restored, the rotorgathers speed and the centrifugal action of the beaters causes them togradually engage the congested material in the casing, crush it, andrestore normal working conditions.

By the construction above described, I have produced a rotor havingradially projecting material engaging elements which are rigid againsttangential movement relative to the rotor, but are adapted to moveinwardly thereof upon contact with unpulverable objects and to beimmediately restored to and held in operative position by thecentrifugal force generated by the revolution of the rotor.

I claim:

1. In a pulverizing apparatus, the combination with a rotor, of beatersmounted upon said rotor each comprising an elongated body portion havinga pivot hearing at one end and a T-head at the other end adapted when inoperative position to engage the material which is to be pulverized, andlugs projecting longitudinally of said beater beyond said head adaptedto engage an element of said rotor to limit pivotal movement of saidbeater as and for the purpose set forth.

2. In a machine of the class described, the combination with a rotorcomprising a shaft and a plurality of discs mounted coaxially thereonand fixed thereto in spaced relation, a pivot bar extending parallelwith said shaft supported in ape'rtures of said discs, reversiblecrushing elements mounted upon said bar for limited pivotal movementeach comprising an elongated body portion and a T-shaped materialengaging head adapted when said body portion is at the outer limit ofits pivotal movement to project beyond the peripheral outlines of therotor or when at the inner limit of its pivotal movement to lie in aninoperative position within said outlines, and means on the rotor tolimit the projection of the beater heads as and for the purpose setforth.

3. In a pulverizing apparatus, the combination with a rotor, ofreversible beaters mounted upon the rotor each comprising an elongatedbody portion having a pivot hearing at one end and a T-head at the otherend adapted to be centrifugally projected to operative position toengage the material which is to be pulverized, and means on the rotor tolimit the projection of the beater heads as and for the purpose setforth.

4. In a machine of the class described, the combination with a rotorcomprising a shaft and a plurality of discs mounted coaxially thereonand fixed thereto in spaced longitudinal relation, a plurality of rodsdisposed in concentric formation relative to said shaft and extendingparallel thereto supported in apertures of said discs, of a plurality ofcrushing elements mounted between said discs and pivotally supportedupon said rods, each of said crushing elements comprising an elongatedbody portion having an aperture at one end through which its pivot rodprojects and extending into close proximity with the succeeding rod, anda material engaging portion adapted to be held by centrifugal force inan operative position projecting beyond the peripheral outlines of therotor or tobe moved by contact with an unpulverable object to aninoperative position within said outlines, and projections adapted toengage saidsucceeding rod to limit pivotal movement of said pulverizingelement as and for the purpose set forth.

5. In a machine of the class described, a rotor, a beater pivoted to therotor on an axis within the peripheral outlines of the rotor, saidbeater comprising an-elongated arm and a transversely projecting head atthe end of the arm remote from the pivotal axis, said head upon rotationof the rotor being centrifugally movable outwardly of the rotorto anoperative position in which the arm lies tangent to'an imaginary circlecon centric with the rotor, the point of tangency being substantiallymidway of the length of the beater and the length of said arm beinggreater than the radius of said circle, said head being movable inwardlyof the rotor upon cessation of the centrifugal force.

6. In a machine of the class described, a rotor;

a beater pivoted to the rotor on an axis within the peripheral outlinesof the rotor, said beater comprising an elongated arm and a transverselyprojecting head at the end of the arm remote from the pivotal axis, saidhead upon rotation of the rotor being centrifugally movable outwardly ofthe rotor to an operative position in which the arm lies tangent to animaginary circle concentric with the rotor, the point of tangency beingsubstantially midway of the length of the beater and the length of saidarm being greater than the radius of said circle, said head beingmovable entirely within the peripheral outlines of the rotor uponcessation or counteraction of the centrifugal force.

'7. In a machine of the class described, a rotor, a beater pivoted tothe rotor on an axis within the peripheral outlines of the rotor, saidbeater comprising an elongated arm and a transversely projecting head atthe end of the arm re mote from the pivotal axis, said head uponrotation of the rotor being centrifugally movable outwardly of the rotorto an operative position in which the arm lies tangent to an imaginarycircle concentric with the rotor, the point of tangency beingsubstantially midway of the length of the beater and the length of saidheater being greater than the diameter of said circle, said head beingmovable inwardly of the rotor upon cessation of the centrifugal force.

8. In a machine of the class described, a rotor, a beater pivoted to therotor on an axiswithin the peripheral outlines of the rotor, said beatercomprising an elongated arm and a transversely projecting head at theend of the arm remote tangency being substantially midway of the lengthof the beater and the length of said beater being greater than thediameter of said circle, said head being movable entirely within theperipheral outlines of the rotor upon cessatrifugally movable outwardlyof the rotor, said head having a longitudinally projecting lug, andabutment means on the rotor for cooperation with said lug to limitoutward movement of said head.

10; In a machine of the class described, a rotor, a reversible beaterpivoted to the rotor on an axis within the peripheral outlines of therotor, said beater comprising an elongated arm and a head at the end ofthe arm remote from the pivotal axis projecting at each side of the arm,said head upon rotation of the rotor being centrifugallymovable-outwardly of the rotor, said beater having a lug projectinglongitudinally from its head end, and abutment means on the rotorcooperating with said lug in one position of the beater to limit outwardmovement of the head and in the reverse position of the beater to limitinward movement of the head.

11'. In a machine of the class described, a rotor, a reversible beaterpivoted to the rotor on an axis within the peripheral outlines of therotor, said beater comprising an elongated arm and a head at the end ofthe arm remote from the pivotal axis projecting at each side of the arm,said head upon rotation of the rotor being centrifugally movableoutwardly of the rotor, the head end of the beater being provided with areentrant recess'having a bounding wall at each side of the longitudinalaxis of the beater, and abutment means on the rotor cooperating withsaid walls to limit the outward and inward movements of said head, thefunctions of said walls being reversed when the beater is reversed. v12. In a machine of the class described, a rotor including a pluralityof rods in parallel relation to the rotor axis, a beater pivoted on eachof said rods in trailing relation thereto, the heaters on adjacent rodsbeing staggered axially of the rotor, and each beater having a portionfor cooperating with' the succeeding rod to limit outward centrifugalmovement of the beater.

13. In a machine of the class described, a rotor including a pluralityof rods in parallel relation to the rotor axis. a beater pivoted on eachof saidrods in trailing relation thereto, the heaters on adjacent rodsbeing staggered axially of the rotor, and each beater having a portionfor cooperating with the succeeding rod to limit outward centrifugalmovement of the beater and inward'movement of the beater when the rotoris at rest. 1 1

14. In a machine of the class described, a rotor includng aplurality ofrods in parallel relation to r the rotor axis, a beater pivoted on eachof said rods in trailing relation thereto, the heaters on adjacent rodsbeing staggered axially of the rotor, each beater comprising an arm witha blaterally projecting head at the distal end thereof adjacent thesucceeding rod, the rear face of the head having a re-entrant recesswith a bound ng face at each side of the longitudinal axis of thebeater, said faces extending to either side of the succeeding rod andcooperating with the latter to limit outward and inward movements of thebeater.

15. In a machine of the class described, a rotor, a beater, said beatercomprising an elongated arm provided with a perforation at one end and abi-laterally projecting head at the other end, the front faces of saidhead being at obtuse angles relative to the arm, the rear face of thehead being provided with a re-entrant recess having a bounding wall ateach side of the longitudinal axis of the arm, a pivot pin on the rotorengaged in said perforation, and an abutment on the ro-.

tor engaged between the bounding walls of said recess to limit pivotalmovement of the beater about said pin.

16. In a machine of the class described, a rotor, a beater, said beatercomprising an elongated arm provided with a perforation at one end and abilaterally projecting head at the other end, the front faces of saidhead being at obtuse angles relative to the arm, the rear face of thehead being provided with a re-entrant recess having a bounding wall ateach side of the longitudinal axis of the arm, the lateral faces of thehead being rearwardly inclined, a pivot pin on the rotor engaged in saidperforation, and an abutment on the rotor engaged between the boundingwalls of said recess to limit pivotal movement of the beater about saidpin.

17. In a machine of the class described, a rotor, a beater, said beatercomprising an elongated arm provided with a perforation at one end and abi-laterally projecting head at the other end, the front faces of saidhead being at obtuse angles relative to the arm, the rear face of thehead being provided with a re-entrant recess having a bounding wall ateach side of the longitudinal axis of the arm, the lateral faces ofthehead being rearwardly inclined on similar arcs, a pivot pin on therotor engaged in said perforation, and an abutment on the rotor engagedbetween the bounding walls of said recess to limit pivotal movement ofthe beater about said pin.

18. In a machine of the class described, a rotor, a plurality of seriesof beaters pivoted to the rotor, the series of beaters being spacedlongitudinally of the rotor and each series comprising a pair of beatershaving diametrically opposite pivot points, the diametric line of thepivot points of one series being substantially at right angles to thediametric line of the pivot points of the succeeding series, heads onthe beaters centrifugally projectible beyond the rotor periphery, andmeans on the rotor limiting such projection, the beater heads beingmovable inwardly of the rotor upon cessation or counteraction of thecentrifugal force, each beater having an effective length substantiallyequal to the distance between its pivot point and a pivot point of thesucceeding series.

19. In a machine of the class described, a rotor including rodsextending parallel to the rotor axis and spaced about the latter atintervals of substantially 90, a plurality of series of beaters pivotedto said rods, the series of beaters being spaced longitudinally of therotor and each series comprising a pair of beaters of which one ismounted upon each of two diametrically opposed rods, the beaters of thesucceeding series being mounted upon the other diametrically opposedrods, heads on the beaters centrifugally projectible beyond the rotorperiphery, and means on the rotor limiting such project-ion, the beaterheads being movable inwardly of the rotor upor' zessation orcounteraction of the centrifugal force, each beater having an effectivelength substantially equal to the distance between its supporting rodand a supporting rod of the succeeding beater series.

20. In a machine of the class described, the combination with a rotorcomprising a shaft, a plurality of discs mounted coaxially on the shaftand fixed thereto in spaced relation longitudinally thereof, a pluralityof rods disposed in concentric formation relative to said shaft andextending parallel thereto, said discs being provided with apertures toreceive and support said rods, of a plurality of crushing elementsmounted between said discs and pivotally supported upon certain of therod portions between the adjacent discs, each of said crushing elementscomprising an elongated body portion having an aperture at one endthrough which its pivot rod passes and a material engaging portionadapted to be held by centrifugal force in an operative positionextending beyond the peripheral outlines of the rotor or to move Withinsaid outlines upon cessation or counteraction of centrifugal force, eachbeater having an open abutment portion for engaging the rod succeedingits pivot rod to limit its outward movement, and being removable andreplaceable without disturbing its abutment rod.

21. In a machine of the class described, the combination with a rotor,of beaters mounted on the rotor, each of said beaters comprising anelongated body portion pivoted at one end to the rotor near the rotorperiphery and a laterally projecting head at the other end adapted to becentrifugally projected beyond the peripheral outlines of the rotor toengage the material which is to be reduced or to move Within saidoutlines upon cessation or counteraction of centrifugal force, eachbeater having an overall length greater than distance between its pivotpoint and the rotor axis and having a freely exposed abutment surface,and abutment elements on the rotor constituted by rotor tie rods andengageable by the abutment surfaces of the beaters to limit outwardprojection of the beaters, the beaters being removable from the rotorWithout disturbing said abutment elements.

22. In a machine of the class described, the combination with a rotor,of beaters mounted on the rotor, each of said beaters comprising anelongated body portion pivoted at one end to the rotor near the rotorperiphery and a laterally projecting head at the other end adapted to becentrifugally projected beyond the peripheral outlines of the rotor toengage the material which is to be reduced or to move with said outlinesupon cessation or counteraction of centrifugal force, each beater havingan overall length greater than the distance between its pivot point andthe rotor axis and having a freely exposed upwardly faced abutmentsurface adjacent its head, and abutment elements on the rotorconstituted by rotor tie rods and engageable by the abutment surfaces ofthe beaters to limit outward projection of the beaters, the beatersbeing removable from the rotor without disturbing said abutmentelements.

23. In pulverizing apparatus, the combination with a rotor, of a beatermounted on said rotor to occupy a position entirely within theperipheral outlines of the rotor and adapted to be projected outwardlyof the rotor by centrifugal force to engage material to be pulverized,said beater comprising an elongated body portion, disengageable pivotingmeans for one end of said beater and located nearer the periphery ofsaid rotor to recede within the latter when engaged material c urse thanthe axis of rotation thereof, and an abutment on the rotor within theoutlines thereof and in trailing relation tosaid pivoting means inposition to be engaged by a free outer surface of said beater to limitthe outward projection thereof when said pivoting means connectssaid-beater to said rotor, the beater in its projected position lyingtangent toanimaginary circle concentric with the rotor, the point oftangency being substantially midway of the length of the beater and thelength of the beater beinggreater than the diameter of said circle, saidheater being removable from the rotor without disturbing said abutmentwhen said pivoting means is disengaged.

24. In pulverizing apparatus, the combination with a rotor, of a-beatermounted thereon and comprising an elongated arm and a headadapted to beprojected approximately radially of the axis of rotation of the rotor.by centrifugal force and to occupy a position entirely within theoutlines of said rotor when the centrifugal force is counteracted, anabutment fixed to the rotor in position to be engaged by a free outersurfaceof said beater to limit the projection of said head, the beaterarm in the projected portion of the beater lying tangent to an imaginarycircle concentric with the rotor, the point of tangency beingsubstantially midway of the length of the beater and the length of saidarm being greater than the radius of said circle and a disengageablepivot means fort-hat end of said beater remote from its head to permitremoval of the beater by withdrawal from said abutment withoutdisturbing the latter.

25. In pulverizing apparatus, the combination with a rotor, of anabutment fixed thereto, a heater comprisingan elongated arm and a headremovably associated with said fixed abutment, and disengageable pivotmeans for that end of said arm remote from said head and locatedrelative to said abutment in position to enable said head to beprojected from the peripheral outlines of the rotor by centrifugal forceuntil an outer surface of the beater engages said abutment, said beaterbeing adapted to occupy a position within the peripheral outlines of therotor when the centrifugal force is counteracted, the beater arm in theprojected position of the beater lying tangent to an imaginary circleconcentric with the rotor,

the point of tangency being substantially midway of the length of thebeater and the length of said arm being greater than the radius of saidcircle, the disengagement of said pivot means enabling said beater to beremoved from the rotor without disturbing said fixed abutment since saidhead is removably associated therewith.

26. In pulverizing apparatus, the combination with a rotor, of anabutment fixed thereto, a beater comprising an elongated arm pivoted tosaid rotor near the periphery thereof and extending along a chordsubtending an arc of at least sixty degrees of the periphery of saidrotor, said heater also comprising a head having a working face movableby centrifugal force to a position projecting from such periphery andfree offers sufl'icient resistance to counteract the centrifugal force,and disengageable pivot means for said beater to permit removal of thelatter without disturbing said fixed abutment, said abutment limitingthe outward movement of said heater.

27. In pulverizing apparatus, the combination with a rotor, of anabutment fixed thereto, a beater pivoted to said rotor near theperiphery thereof and comprising an elongated arm and an operating head,said beater being removably associated with said abutment in position tolie wholly within the peripheral outlines of saidrotor or to beprojected therefrom by centrifugal force to an extent predetermined bysaid abutment, the length of said beater being greater than the diameterof an imaginarycircie concentric with the axis of said rotor and tangentto the said arm substantially midway between its ends when the heater isfully projected, and removable pivot means for said beater to enableremoval of the latter from the rotor by disengagement from said abutmentwhile the latter remains fixed to said rotor.

28. In pulverizing apparatus, the combination with a rotor, of a fixedabutment thereon, a heater comprising an elongated arm and a workinghead, spaced-apart lugs projecting from the outer end of said beater andforming a shallow U-shaped recess removably associated with said fixedabutment, and disengageable pivot means for said heater in position tosupport the latter for movement by centrifugal force approximatelyradially of the rotor axis and for automatic movementto a positionwithin the peripheral outlines of the rotor when said centrifugal forceis counteracted by the beater striking abnormally hard materiah ,29. Inpulverizing apparatus, the combination with a rotor, of a beater pivotedto the rotor on an axis within the peripheral outlines of the latter andparallel to the rotor axis, said beater comprising an elongated arm anda head having a working face remote from said axis and projectedentirely under centrifugal force in an approximate radial directionbeyond the peripheral outlines of the rotor upon rotation of the latter,and means for limiting the outward movement of the said working face,the said head being adapted to move entirely within the peripheraloutlines of said rotor upon counteraction of the centrifugal force, thelength of said beater being such that when said working face isprojected as aforesaid, a plane through the rotor axis intersecting saidworking face shall be angularly spaced more than forty-five degrees froma plane extending through said rotor axis and the pivotal axis of saidbeater.

30. In pulverizing apparatus, the combination with a rotor, of a beaterpivoted to the rotor on an axis within the peripheral outlines of therotor and parallel to the rotor axis, said heater having a head portionremote from its axis projected entirely by centrifugal force in anapproximately radial direction beyond the peripheral outlines of therotor upon rotation of the latter, means on the rotor for limiting theoutward movement of the head portion, said head portion being adapted tomove entirely within the peripheral outlines of the rotor uponcounteraction of the centrifugal force, the length of said heater beingsuch that when said head portion is projected as aforesaid, the beateroccupies a position wherein it subtends an arc of the periphery of morethan sixty degrees.

31. In pulverizing apparatus, the combination with a rotor, of a heaterpivoted to the rotor on an axis within the peripheral outlines of therotor, said beater comprising an elongated arm and a projecting headhaving a working face at that end of said arm remote from its pivotalaxis, said working face upon rotation of the rotor being centrifugallymovable outwardly of the rotor to an operative position in which saidarm is'one side of a triangle, of which the other sides are radiiextending from the axis of rotation of the rotor through the pivotalaxis of the heater and the outer end of said arm, respectively, and atleast sixty degrees apart, the said working face being adapted to recedeto a position within the rotor periphery when the centrifugal force iscounteracted by such working face striking abnormally hard material, andmeans on the rotor for limiting the projection of said working face.

32. In pulverizing apparatus, the combination with a rotor, of a beaterpivoted to said rotor within and near the periphery thereof, said beatercomprising an arm with a working face on the outer end thereof inposition to project from the rotor and occupy an operative position on aradius extending through the rotor axis, and means forlimiting theprojection of said working faceto a position where said arm is one sideof a triangle of which the other sides are radii from the rotor axisthrough the pivotal axis of said beater and through said working face,respectively, and at least sixty degrees apart.

33. In pulverizing apparatus, the combination with a rotor, of a beaterpivoted to the rotor near the periphery thereof and comprising an armhaving a length approximately equal to the distance between the rotoraxis and the pivotal axis of said beater, said beater having also a headat the outer end of said arm with a working face adapted to be projectedby centrifugal force from the periphery of said rotor, said working facereceding to a position within the peripheral outlines of the rotor whenthe centrifugal force is counteracted, and means on the rotor engageableby the beater for limiting the projection of said working face.

34. In pulverizing apparatus, the combination with a rotor, of a beaterdisengageably pivoted to the rotor near the periphery thereof andcomprising an arm having a length approximately equal to the distancebetween the rotor axis and the pivotal axis of said beater, said beaterhaving also a head at the outer end of said arm with a working faceadapted to be projected by centrifugal force from the periphery of saidrotor, said working face receding to a position Within the peripheraloutlines of the rotor when the centrifugal force is counteracted, and alug projecting from the head end of said beater in position to engage anelement of said rotor to limit pivotal movement of said beater, said lugbeing disengageable from said rotor element without disturbing thelatter upon disengagement of the beater pivot.

35. In pulverizing apparatus, the combination with a rotor, of a beaterdisengageably pivoted to the rotor near the periphery thereof andcomprising an arm having a length approximately equal to the distancebetween the rotor axis and the pivotal axis of said beater, said beaterhaving also a head at the outer end of said arm with a working faceadapted to be projected by centrifugal force from the periphery of saidrotor, said working face receding to a position within the peripheraloutlines of the rotor when the centrifugal force is counteracted, andmeans on said head affording a U-shape open recess in position to beassociated with an element of said rotor to limit the pivotal movementof said beater, the beater being removable from the rotor upondisengagement of the beater pivot without disturbing said rotor element.

NILS D. LEVIN.

